The problem with metrics is that there is no one metric that fits all investors and situations.
Looking at some of the enervation shows on TV, the price they pay and what they put into the property would never work in the markets we have experience in. A 3/2 in CA is a bargain for $300K while in our markets, $300K would get you a move in ready 4/2 on the water. So for us to use a metric that looks at having to make $100K on a deal to make it worthwhile is a non-starter. The seller would have to be paying us to take the property if we wanted to make that amount.
We make use of the tools here on BP to help frame out a deal as well as using our knowledge of the local market to gauge what a property will be worth renovated. We know what the cost is to pay for some work and determine if we do some ourselves, is the time vs money a route to go. We also look at how fast we can complete the project. If we can get in and out in 30-45 days on a cosmetic flip, we will take less profit than a 6 month or longer rehab. Having professionals we can call to see how backed up they might be factors in as well - if we can't get a roof done ASAP, that holds everything else up if we have a leak so again, more time, more holding costs, lower ROI.
Unfortunately I do not think there is a magic metric that can tell you if the deal is a winner or not. It comes down to factors like your area, your market, your experience, the team you can draw from and how mush you need to make to support the investment of time and capital. If you are pulling a HML, you need to fully understand the cost of money which can break a deal with one thing going wrong in the process.
Hope this helps and I am happy to discuss this further if you want to PM me.